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DNA Flashcards

1
Q

who waas the pioneer of nucleaic acids?

A

Fredrick meisccher

Pheobus levene

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2
Q

what did fredrick meischner do?

A

wanted to isolate chemicals of white blood cells
isolated cells from surgical bandages
found it was acidic
named it nucleic acid

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3
Q

what did pheobus levene do?

A

identified DNA molecules have a phosphate sugar backbone, named this a nucleotide
propsed DNA is a reapeating unit
did the chemistry to work out components

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4
Q

purines

A

A,G

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5
Q

pyridamines

A

C,T,U

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6
Q

which way are the carbonds numbered

A

right to left

ending on the to one

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7
Q

which way do we read DNA

A

5 to 3 prime

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8
Q

evidence of DNA being heriditary experiment

A

2 strains of pneomococci causing pneumonia

griffths

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9
Q

pneumococci experminet detail

A

mouse infecjectd with either strain R or S
with strain S, die, with R survives
heat kill S and inject, still fine
mix r and s and kills

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10
Q

what is starin R and S

A

R is benign

S is virulent

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11
Q

what did the mouse pneumocci experiment show?

A

something from the dead S cells goes to the R cells to make them virulent and they can be revives

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12
Q

what did Avery do?

A

remove lipids and carbs from heat killed S cells
proteins, RNA and DNA remain
treat to remove either of these last three
obverse transformation or not

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13
Q

what did Avery find?

A

No protein: tranfomed
No RNA: tranformed
no DNA: nothing
proved proteins NOT heriditary but DNA is

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14
Q

what did hershey and chase do?

A

bacteriophage heriditay material

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15
Q

what did the bacteriophage heriditay material expeiment show?

A

the molecule transfered between bacterial cells was DNA and not protein
if replication continued, daughters would be radioactive due to DNA

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16
Q

what did edwin cargaff do?

A

work out the ratio of bases

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17
Q

how did the ratio of bases get woked out?

A

edwin cargaff
take tissues and extract the DNA and trea them
hydrolyse leaving free nucleotides
sepearate them using paper chromaotgraphy
measure the number of bases using UV spectromoetry

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18
Q

what did edwin cargaff conclude

A

amount/ percentage of bases differed between species and the poportions are always the same and add up to one

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19
Q

whatis the chargaff rule

A

amount/ percentage of bases differed between species and the poportions are always the same and add up to one

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20
Q

who all showed that DNA is hereidiatry material

A

griffiths
avery
hershey and chase

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21
Q

how did X-ray difffraction help show DNA structure

A

using crystal of the molecule the diffraction pattern is very unique
made two patterns of diffraction, A and B.
found helical shape

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22
Q

how did watson and crick made a DNA model

A

negative phosphates repel each other, these on outside
base pairs line up inside and are same equal lengths
mode made with tin plates, antiparalel chains

23
Q

features of watson and cricks DNA model

A 
two aniparalel strands
10 pairs per strand
riht handed helix
bases perpedicuar to helixal axis
helix not symetrical
minor and major groove
24
Q

what did mesleton and sthal show?

A

repication of DNA is semi-consevative

25
what experiment showed semi conservative replication
``` grew ecoli in N15 all DNA radio labelled swap to N14 media new dna now grows with this centrifuge for density gradient repeat wth new colony in N15 found at end that most DNA had half a half, some from parents and some from new in the growth media, showing semi-conservative ```
26
why is replication complicated?
strands run in opposite directions
27
how does polymerase work to overcome replication issues?
only reads 3-5 direction and synthesises 5-3 discontinuous way of working causes the strands to swap over
28
what is the central dogma
``` information flow in cells replication transciption from DNA to RNA then translation into proteins and reverse using revere transciption ```
29
how gave evidce mRNA is the messenger?
elliot volkin
30
what did elliot volkin do?
lysed cells, treated nucleic acids with NaOH analysed with ion chromatography after infection, large activity with synthesis of acids DNA of phage transcrbed into mRNA
31
how does transciption work?
one strand trascrbed in each gene | starts at defined point, promoter sequence
32
what way is the DNA sense strand
5-3
33
what way is the DNA anti-sense strand
3-5
34
what way does RNA polymerase read
3-5 reading
35
whaich way is translation to make proteins
5-3
36
how do enzymes work on DNA
read 3-5 | synthesise 5-3
37
what is the new RNA strand complementary to?
DNA anti-sense
38
what is the structure of mRNA in eukaroyotes
5 end cap methylation modification 3 prime untranslated region, AAUUAAA equals end of transciption poly A tail added for stability
39
what is 5 end cap methylation used for
involved to get in ad out of the nucleuc | introns and exons too
40
how are introns removed?
splicin via small nuclear ribonucleapproteins snRNPs
41
what are the consequences of RNA splicing
``` alternative proteins new stop codons reading frame changes proteins with different modules or regulator elements different proteins from same genes ```
42
whats alernatve splicing
allows eukaryotic organisms to increase genes by 2-3 times
43
how were the number of amino acids worked out? and the genetic code features
Brenner and phage mutants
44
what did brenner find?
code is degenerate, non-overapping and works in units of three
45
what did Nirenberg work out?
how translation worked
46
what did nirenberg do?
Poly U experiment By measuring the amino acids that were incorporated into protein it was possible to show that the RNAs from different sources were making different proteins.
47
ribosome structure
reads 5-3 parts: - A site - P site - E site
48
what is tRNA
uncodes the RNA and links correc amino acid
49
three stages of translation
initiation elongation termination
50
describe initiation of translation
``` mRNA binds to small ribosomal subuni complex binds to tRNA binds to large sub-unit now binds into P site cycle to next part ```
51
describe elongation of translation
next tRNA binds to next bases of rna filling site A join two amino acids in chain transloaction from site P to A whole thing shifts tRNA moves aong from A to P, another goes from E and dissociates
52
order of binding sites on a ribosome
E, P, A
53
describe the proces of termination in translation
continues untill reaches a stop condon release factor binds to stop codon dissocated from whole complex cycle stops
54
process of translation in short
``` P site chain moves A site filled translocation E site removal ```

Building blocks of life (17 decks)

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